The present invention is related to brake pads for disc brakes and in particular to the mounting arrangement therefore.
Disc brake pads that are adapted for use in certain railroad installations employ a dovetail configured backing plate via which the brake pad is affixed to a brake shoe holder having a corresponding dovetail shaped groove to receive the backing plate dovetail. This dovetail groove has a generally vertical orientation in the brake shoe holder, which allows the backing plate dovetail to be installed from the bottom until its forward or upper end engages the adjacent closed upper end of the dovetail groove. Various type locking pins or clasp arrangements are utilized to close the bottom opening of the dovetail groove following brake pad installation in order to prevent the brake pad from falling out during service and to accommodate removal during changeout of worn or damaged brake pads.
The backing plate is made of thin steel sheet stock, which is well-suited for forming the dovetail-shaped tongue by a stamping/forming operation. While the thin steel sheet makes possible a cost-effective means of forming the dovetail-shaped backing plate, deformation of the dovetail has been found to occur in actual service at its upper or forward end. This deformation results from the running vibration of the railroad car, which is transferred to the vertically oriented disc pad, and in turn causes the upper end of the backing plate dovetail to vibrate against the upper end of the dovetail groove. This repetitive impingement of the dovetail upper end causes the end to be peened into the dovetail groove. Consequently, when brake pad removal or change-out is required, interference between the peened end of the dovetail and the dovetail groove makes it difficult and time consuming to remove the brake disc which is intended to be accomplished by simply sliding the backing plate dovetail out of the dovetail groove.